134 
[Assembly 
There are, doubtless, in other parts of the district, large depo- 
sites of this ore which have not yet been discovered on account 
of the dense forests vv^hich cover the surface and render examina- 
tion laborious and difficult. Time, however, will develope these 
valuable resources, and enterprise and industry will render them 
available, notwithstanding their secluded and almost inaccessible 
position. 
Origin of Ore. 
With regarid to the source or origin of the magnetic ores, there 
can be no doubt but they are as much an original formation as the 
rocks in which they are embraced. It has been before stated that 
these beds have the same bearing as the rocky ranges. The gran- 
ite forming the walls, or roof and floor, has particles of ore dis- 
seminated through it, decreasing in quantity as we recede from 
the bed. These particles could not have found their way into the 
rock, if the ore had been projected into fissures or between strata 
after the rock had become in any degree consolidated. From these 
and many other circumstances, we infer that the conditions, as 
respects fluidity, must have been the same in the rock as in the ore. 
Phenomena of Dykes. 
Few beds have been sufficiently wrought to develop the effects 
produced by dykes, (or as the workmen here call them, horses^) 
although they are observed in almost all beds which have been 
worked. By a dyke, is meant a wall or vein of mineral matter, 
different from the ore or rock which it traverses. The dykes trav- 
ersing these beds of ore are commonly vertical, or nearly so. A 
knowledge of the changes produced by dykes, and the best methods 
of obviating the difficulties arising from ihem, is of much import 
ance to the practical miner. 
A dyke crossing at right angles to the course of a bed of ore, 
causes no change in its direction; but a dyke crossing obliquely to 
the course of a bed, causes a dislocation, or turning of the bed 
from its course, in proportion to its obliquity and thickness. The 
most westerly of the Arnold beds, which has been worked for the 
distance of 80 rods, is crossed by ten dykes, from one inch to 16 
feet in thickness; most of them are at right angles, or so little 
oblique as to cause only a few inches variation in the course of 
the bed: two of these however, crossed at an angle of about 45*^, 
causing a dislocation of the bed of almost its entire width. In 
